Hashimoto’s encephalopathy – rare but reversible cause of dementia or psychosis

Abstract

Hashimoto’s encephalopathy is a rare condition associated with Hashimoto’s thyroiditis. It is also described as steroid-responsive encephalopathy associated with thyroid autoimmunity due to the good clinical response to treatment with steroids. It is an encephalopathy, with acute or subacute onset, which may manifest as dementia, disturbances of consciousness, psychosis, frequently accompanied by seizures, tremor, myoclonus, ataxia, and stroke-like episodes. HE is a rare disease with a recent estimated prevalence of 2.1/100,000. HE was first described in 1966 by Brain et al., and since its first description, more than 100 patients have been reported in the literature as having Hashimoto encephalopathy. Thyroid gland dysfunction in HE may be variable: from patients presenting hypothyroidism, those who are euthyroid to patients with hyperthyroidism. AntiTPO antibodies are present in 95-100% of cases, and anti-Tg antibodies in 73% of patients with HE. To support the diagnosis CSF protein level should be assessed, which is typically elevated. The treatment of HE is usually with oral prednisone or high dose of intravenous methylprednisolone, which should cause resolution of neurological symptoms. The condition seems to be presently underdiagnosed, so, it is important to have a clinical suspicion for HE in patients with clinical manifestation of dementia or psychosis, as it is a readily treatable condition with good prognosis.